Retrogenesis is the biologic process by which normal physiologic, psychologic, and behavioral processes in the course of dementia reverse those of normal human developmental acquisition. Relationships between normal human development and dementia have long been recognized. For example, the ancient Greek playwright Aristophanes noted in 423 B.C. that “old men are children twice over”. Similarly, the English dictionary defines dotage, a synonym for dementia and related conditions, as “childishness of old age”. Physicians and scientists have also recognized similarities between senile dementia and normal early human development. For example, in the first American textbook of psychiatry, Benjamin Rush (1793), noted that in old age the body shows the marks not only of a second childhood but even the marks of second infancy. In the twentieth century investigators began to find relationships between Piagetian developmental stages and degeneration occurring in dementing disorders.
In 1982 Dr. Reisberg and associates published the Global Deterioration Scale, which described seven major stages of normal aging and the progressive dementia of AD. Later, in work published from 1984 to 1986, Dr. Reisberg identified the characteristic progression of functional changes in normal aging and progressive AD. Sixteen successive functional stages were described. It was immediately recognized by Dr. Reisberg that this functional progression in aging and AD reversed the stages of functional acquisition in normal human development. Subsequent work by Dr. Reisberg and his colleagues also indicated that the pattern of loss of feeding capacities and figure drawing abilities in AD reversed the normal acquisition pattern in early human development. Together with Dr. Emile Franssen, Dr. Reisberg found that: (1) normal infantile neurological reflexes emerge in the course of AD, and (2) that these reflexes occur at the same point in AD, from the perspective of the inverse functional stage, as would be anticipated from the human developmental model. This discovery of a method for diagnosis of incontinence of corticocerebral origin by neurologic examination has been previously described in U.S. Pat. No. 5,826,585 awarded to Dr. E. H. Franssen and Dr. B. Reisberg.
In other work by Dr. Reisberg and his associates it was found that childhood and infant psychological test measures are useful in assessing residual cognitive capacities in, what was previously termed “untestable”, severe AD. These findings are described in U.S. Pat. No. 5,082,446 awarded in 1992 to Dr. S. G. Sclan and Dr. B. Reisberg. Work by other investigators, indicated that a widely used dementia assessment, the Mini Mental State Examination, showed just as robust relationships between the mental age of children, as has been observed for the relationship between Mini Mental State Examination scores and any independent objective, non-cognitive assessments in AD patients.
On the basis of the findings described above, as well as other findings, it was concluded in 1998 that the stages of AD can be usefully described in terms of corresponding developmental ages (DAs) (Reisberg, et al., J Neural Transm,[Suppl] 54: 9–20, 1998). We noted that the management needs of AD patients and many of the behavioral changes in these patients could be explained by the DA model.
Later, in 1999, we concluded that the process by which the progressive changes in AD and related dementing disorders reverses the order of acquisition in normal human development should be given a new and appropriate name. Therefore, we termed this process, “retrogenesis” (Reisberg, et al., International Psychogeriatrics, 11: 7–23, 1999 and Reisberg, et al., Eur Arch Psychiatry Clin Neurosci 249: Suppl. 3, 28–36, 1999). We hypothesized that an entire science of management for AD and related dementing disorders could be formulated based upon an understanding of this retrogenesis process. We also hypothesized at that time that this understanding would have to incorporate both similarities and differences between AD and normal human development.